What affects the brightness of a light bulb?

Question

Is it voltage or current? Or is it something else? Could you further explain? Thanks

Answer 1

Both. P = iV where
P = power in watts
i = current in amperes
V = voltage in volts

Voltage is pretty standard at 110V (in the US) so a bulb's wattage is determined by the current that the filament handles.

Answer 2

Hi,
Light from a bulb is caused by electrons vibrating in the filament, and, as you know, when electrons are accelerated, they give off energy. If the energy is sufficiently high, the photons react with the eye and produce a sensation of light. a
Now, what causes the heating? The power dissipated in the filament. And that power dissipation is a product of voltage and current or the current squared times the resistance.
P = EI
Also, P = I^2R.
So, you can't really isolate the voltage and current as causes. The voltage causes the current flow, and the current flow is limited by the resistance.

Hope this helps.
FE

Answer 3

The resistance of the bulb is built-in to the element within the bulb, obviously you cannot change that. So, the brightness can only be determined by the voltage you put across the bulb. The current is a function of the impedance of the bulb and the voltage across it. You could put a rheostat into the circuit with the bulb which essentially changes the impedance of the bulb, but that will burn as much power dim as it does bright. There is a circuit called a triac which will do the same, but not cost as much power.

Answer 4

It is the current through the resistive filament. The resistance of the filament increases as it gets hotter and as it gets hotter, more power is dissipated.
Power = I^2 R